Has never been significantly overweight; maybe at worst a bit pudgy eating absolute garbage 24/7. They do not have adipocyte hyperplasia, so their adipose is IR.

They almost always have high SNS, low parasympathetic, are IR
at baseline. They will typically exhibit high blood sugar fasting,
tend to other SNS symptoms like sweating/being overheated , high blood
pressure, fat storage around abdomen, very little white adipose storage
in limbs. They were usually slim in youth, without much if any effort
and are naturally athletic in youth as well.

Because they have high SNS tone and IR white adipose, fat binging is grossly insufficient to prompt adipose growth;
blood ketones can become very high due to IR, and they will feel very
energetic even not eating for many hours due to high fat oxidation
(sympathetic mediated).

This person is in a TOTAL DIFFERENT BIOLOGICAL REALITY to your constitutional fat ass. Here is wooo reality: